"They demand that Iran makes a quick decision, (insisting that) time is limited and Iran must respond quickly," foreign ministry spokesman Nasser Kanani said at his weekly news conference, referring to Western parties to the nuclear deal.

Kanani said the Islamic republic will "not sacrifice the country's fundamental interests... with a rushed process".

It was being put under "psychological pressure and unilateral expectations", he said.

But "if the US acts constructively and positively, an agreement is close," Kanani said.

The 2015 agreement gave Iran sanctions relief in exchange for curbs on its atomic programme to guarantee that it could not develop a nuclear weapon -- something it has always denied seeking.

But the US' unilateral withdrawal from the accord in 2018 under then-president Donald Trump and Washington's reimposition of biting economic sanctions prompted Iran to begin rolling back on its own commitments.

Talks in Vienna that started in April 2021 to restore the deal have stalled since March amid differences between Tehran and Washington on several issues.

The two sides negotiated indirectly through the European Union coordinator.

Qatar hosted indirect talks last month between the United States and Iran in a bid to get the Vienna process back on track, but those discussions broke up after two days without any breakthrough.

On Thursday, State Department spokesman Ned Price said Iran "doesn't seem to have made the political decision -- or decisions, I should say -- necessary to achieve a mutual return to compliance" with the deal.

France's envoy to the UN, Nicolas de Riviere, in June urged Iran to "seize without further delay the offer on the table".

French President Emmanuel Macron on Saturday told his Iranian counterpart Ebrahim Raisi that reviving the landmark deal was "still possible" but must happen "as soon as possible".

Macron's comments came after Britain's spy chief voiced doubt that the deal can be revived, saying Iran's supreme leader and ultimate decision-maker Ayatollah Ali Khamenei remained opposed.

"I don't think the supreme leader... wants to cut a deal. The Iranians won't want to end the talks either so they could run on for a bit," MI6 chief Richard Moore said late last week.